New fella here with more ambition than common sense.

so, thank you all for having this site and helping newer guys like myself out, I'm no stranger to sfx, silicone, prop/costume making. So I felt like it was time to pull the trigger and join a site with the pros!

My current project is this monster, carnage the spiderman villain, my goal is to have em done by Halloween (10 ish days) as my son is going to be spiderman. So, I have a few questions, I'm going to run silicone in these molds (dragon skin 10 NV) through a pour spout in the back of the head, after I fill in the teeth of course, as I feel they are going to be a pain and I just want to get it right the first time around.
My most recent joint project venture included making a smaller polyester fiberglass mold to run silicone through for the Cyberpunk cosplay contest and I learned so much from that process!
I suppose I am posting to see if you guys had any insight or things/tips that I may need prior to going into this beast. I'm not scared of it, just wanna make sure I have all of my bases covered.

So, lastly I did plan on making some movable tendrils for this costume as carnage can have quite a few. I originally thought about making them electronically actuated but have sense considered doing them the old fashion way with strings and springs. Essentially puppeteer mechanics that will attach to segmented rings on my fingers. 
Any advice on that at all? I really appreciate you guys reading everything here i tend to like to rant when it comes to these projects because frankly, the wife is over it. 
Thanks in advance!